The file of this patent application includes duplicate copies of a compact disc with a file entitled xe2x80x9cP0346 code.txtxe2x80x9d, created on May 30, 2001, and having a size of 92,072 bytes (92,160 bytes on disc), which is hereby incorporated by reference.
The present invention relates to video signal processing, and more particularly relates to the processing of such signals to embed auxiliary data (e.g. identification or control data therein), and the subsequent extraction and use of such data.
In accordance with an illustrative embodiment of the present invention, an input content signalxe2x80x94representing audio or videoxe2x80x94is encoded to hide plural-bit auxiliary data therein. The process generates an intermediate signal that is a function of (a) the plural-bit auxiliary data, and (b) data related to human perception attributes of the content signal. This intermediate signal is then summed with the content signal to effect encoding.
The plural-bit auxiliary data can include copy control data, i.e., data that can be sensed by a consumer electronic device and used to disable a copying operation. The auxiliary data can also include an index or pointer to remotely-stored data that relates to the encoded content.
The intermediate signal may include a pseudo-random key signal so as to obscure the encoding and require knowledge of a corresponding key at the decoder to extract the auxiliary data from the encoded content.
In some embodiments, calibration data is encoded in the content signal with the auxiliary data. (The calibration data may form part of the auxiliary data or may be distinct.) This calibration data desirably has known properties (e.g., spectral attributes, data content, etc.) facilitating its identification in the encoded content signal.
The encoding is desirably robust against various forms of content degradation, e.g., lossy compression/decompression, scaling, resampling, conversion from digital to analog and back again, etc. so that the auxiliary data can be detected from the content notwithstanding such corruption.
In some embodiments, each sample of the content signal is encoded in accordance with a single bit of the auxiliary data. In others, at least some samples are encoded in accordance with plural bits of the auxiliary data. In some embodiments, neighboring samples in the content signal may be encoded in accordance with a common-bit orxe2x80x94bits of the auxiliary data. In some cases neighboring samples may be encoded in accordance with plural bitsxe2x80x94some common between the samples and some different.
Decoding of the auxiliary data from the encoded content can be accomplished by various techniques, some of which can rely on statistical analysis of the encoded content.